title: Would increasing centre volumes improve patient outcomes in peritoneal dialysis? A registry-based cohort and Monte Carlo simulation study.
abstract: OBJECTIVE
  To estimate the association between centre volume and patient outcomes in peritoneal dialysis, explore robustness to residual confounding and predict the impact of policies to increase centre volumes.
  
  
  METHODS
  Registry-based cohort study with probabilistic sensitivity analysis and Monte Carlo simulation of (hypothetical) intervention effects.
  
  
  METHODS
  112 secondary-care centres in France.
  
  
  METHODS
  9602 adult patients initiating peritoneal dialysis.
  
  
  METHODS
  Technique failure (ie, permanent transfer to haemodialysis), renal transplantation and death while on peritoneal dialysis within 5 years of initiating treatment. Associations with underlying risk measured by cause-specific HRs (cs-HRs) and with cumulative incidence by subdistribution HRs (sd-HRs). Intervention effects measured by predicted mean change in cumulative incidences.
  
  
  RESULTS
  Higher volume centres had more patients with diabetes and were more frequently academic centres or associative groupings of private physicians. Patients in higher volume centres had a reduced risk of technique failure (>60 patients vs 0-10 patients: adjusted cs-HR 0.46; 95% CI 0.43 to 0.69), with no changed risk of death or transplantation. Sensitivity analyses mitigated the cs-HRs without changing the findings. In higher volume centres, the cumulative incidence was reduced for technique failure (>60 patients vs 0-10 patients: adjusted sd-HR 0.49; 95% CI 0.29 to 0.85) but was increased for transplantation and death (>60 patients vs 0-10 patients: transplantation-adjusted sd-HR 1.53; 95% CI 1.04 to 2.24; death-adjusted sd-HR 1.28; 95% CI 1.00 to 1.63). The predicted reduction in cumulative incidence of technique failure was largest under a scenario of shifting all patients to the two highest volume centre groups (0.091 reduction) but lower for three more realistic interventions (around 0.06 reduction).
  
  
  CONCLUSIONS
  Patients initiating peritoneal dialysis in high-volume centres had a considerably reduced risk of technique failure but simulations of interventions to increase exposure to high-volume centres yielded only modest improvements.
authors.affiliation: UMR-S 707, Inserm, Paris, France.
authors.forename: David
authors.initials: D
authors.lastname: Evans
authors.forename: Thierry
authors.initials: T
authors.lastname: Lobbedez
authors.forename: Christian
authors.initials: C
authors.lastname: Verger
authors.forename: Antoine
authors.initials: A
authors.lastname: Flahault
keywords: Confounding; Intervention simulation; Peritoneal dialysis; Sensitivity analysis; Volume-outcome association